Performance Investigation of Compound Parabolic Concentrator Integrated Collector-Storage Solar Air Heater

A type of compound parabolic concentrator integrated collector-storage solar air heater was presented in this paper, which took flat micro heat pipe arrays as the core heat transfer element, combined with compound parabolic concentrator and latent heat storage unit. The system took compound parabolic concentrator vacuum tube collector as the heat collecting part, 58# paraffin as the latent heat storage material, and the lap joint-type flat micro heat pipe arrays as the core heat transfer element. The thermal storage and release performance of the system under two different modes (discharging after charging and charging while discharging mode) was tested outdoors. According to the change of the azimuth angle of the sun incident lights, combined with the incident half angle θ of the concentrator, the time range of the total solar radiation absorbed by the concentrator was determined, and the absorption model of the solar radiation energy by the compound parabolic concentrator was established. Results show that under the mode of charging after discharging, the solar radiation absorbed by the collector is about 15 MJ, the average heat storage efficiency is about 36%, and the change of air flow has little influence on the daily total efficiency of the device, maintaining at about 34%. Under the mode of charging while discharging, with the increase of air volume flow, the useful energy extracted increases, and the daily total efficiency of the device increases. When the air flow is 110 m³/h, the useful energy extracted is 7.07 MJ, and the daily total efficiency is 45.6%.